The scaling of semiconductor device structures, such as, for example, complementary metal-oxide-semiconductor (CMOS) devices, has led to significant improvements in speed and density of integrated circuits. However, conventional device scaling faces immense challenges for future technology nodes.
One approach to improve semiconductor device performance is to enhance the carrier mobility, and consequently the transistor drive current, utilizing strain induced effects. For example, it has been shown that the hole mobility may be considerably enhanced in a p-channel silicon (Si) transistor employing stressor regions, such as, stressor regions employed in the source and drain regions of the transistor structure.
The contact resistance to the active regions of a semiconductor device structure may be a concern for on-going device improvement at future technology nodes. For example, for CMOS device structures, the contact resistance may include the electrical resistance between the contact structure and one or more stressor regions comprising the source and drain regions of the transistor structure. In the case of an n-type MOS device, the stressor region may comprise a highly doped region, i.e., with a carrier density of approximately 5×1020 cm−3, doped with either phosphorus or arsenic. The high doping levels that may be achieved in the n-type MOS device stressor region may result in a contact resistivity as low as 0.3 mΩ-cm. However, for the p-type MOS device, the current state of the art has focused on the use of boron p-type doping utilizing a boron dopant precursor, such as, diborane (B2H6). The use of diborane (B2H6) in p-type MOS devices may result in a carrier density of approximately 1×1020 cm−3. Efforts to increase the p-type carrier density in p-type MOS devices by the addition of further boron may result in a decline in the crystalline quality of the doped stressor region and may not significantly contribute to the active carrier density in the p-type stressor region. Accordingly, alternative methods and precursors are desired that would enable high p-type doping densities in semiconductor materials, such as, for example, Group IV semiconductor materials.